nitrogen fixers

Discussion in 'HortForum' started by grnpinkie, Aug 20, 2006.

  1. grnpinkie

    grnpinkie Member

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    When a plant is described as fixing nitrogen in its roots, does that mean that if you planted it in a lawn it would deplete the nitrogen available for the grass roots?
     
  2. pierrot

    pierrot Active Member 10 Years

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    Hello grnpinkie

    Nitrogen fixing is a function of the legume plants where they symbiotically use a bacteria to remove nitrogen from the air and use it for plant growth.

    Nitrogen occurs as a gas and is converted into an insoluable form nitrites ( chem formula NO2 not water soluable). plants cannot use the gaseous form or the nitrites and need nitrates (chem formula NO3, water soluable). Usually a bacteria such as Rhizobium will remove the gaseous form and also use the nitrite and convert it into the nitrate form. this is water soluable and the plant can use it. The bacterial inturn use the roots of the plant as a safe haven.

    this is most recognizable in the peas and bean but all their relatives (the legumes) have the ability to do this. this usually means that the legumes can colonize areas that do not have high soluable Nitrate quantities. It can also be seen in Red Alder where another bacteria Frankia is used for the same effect

    if the area is high in nitrates in the first place e.g. in a lawn area where we pour large quantities of nitrate onto it to keep it green, the process of fixing nitrogen is often turned off as the plant does not need to have this relationship as we have provided enough for survival. then yes Planting anything in a grass lawn will compete with the grass for nitrogen and increase the need for more synthetic fertilizers to keep it green contributing to more run off and more pollution in the lakes and waterways...



    but then lawns are evil and should be replaced with anything else!!!
     
  3. grnpinkie

    grnpinkie Member

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    Hi Pierrot,

    Thanks for your reply.
     

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